I have a problem where I can't talk to be people unless they talk to me first a number of times before I can feel comfortable enough to strike up conversation with them.
If they say hello to me enough times then I'll feel comfortable greeting them in the morning without being greeted first. But if they don't, then I won't.
I don't hold it against people for not liking me though because I don't initiate conversation with them.
oh, and if you're a dark-skinned office-worker or you live in Chicago/Detroit/similar latitude, don't bother checking in --- you're automatically in the risk zone.
Do you live in a medium/big town? I live in a 10k German village and it's mostly old people that appreciate to greet strangers I guess, however today while riding my bicycle some 20yo semi-cute girl walking her dog also smiled and greeted me just because I was staring at her and put on my white people smile face. Another time I rode past some balkanoid looking teenagers and they said hello but I was already 2-3m past them and it was too awkward to say hello back so I just ignored it. Germanoids in general just love greeting each other I would say, Slavoids probably not so much